Few relationships are as important to stability in Asia as the one between Japan and South Korea. Yet Japan’s new prime minister, Shinzo Abe, seems inclined to start his tenure with a serious mistake that would inflame tensions with South Korea and make cooperation harder. He has signaled that he might seek to revise Japan’s apologies for its World War II aggression, including one for using Koreans and other women as sex slaves.

In 1993, Japan finally acknowledged that the Japanese military had raped and enslaved thousands of Asian and European women in army brothels, and offered its first full apology for those atrocities. A broader apology by Prime Minister Tomiichi Murayama in 1995 conceded that “through its colonial rule and invasion,” Japan had caused “tremendous damage and suffering to the people of many countries, particularly to those of Asian nations.”

In an interview with the Sankei Shimbun newspaper, Mr. Abe, a right-wing nationalist, was quoted by Reuters on Monday as saying he wants to replace the 1995 apology with an unspecified “forward looking statement.” He said that his previous administration, in 2006-7, had found no evidence that the women who served as sex slaves to Japan’s wartime military had, in fact, been coerced. However, at a news conference last week, the chief cabinet secretary, Yoshihide Suga, said that Mr. Abe would uphold the 1995 apology but hinted he may revise the 1993 statement.

It is not clear how Mr. Abe, the leader of the Liberal Democratic Party of Japan, might modify the apologies, but he has previously made no secret of his desire to rewrite his country’s wartime history. Any attempt to deny the crimes and dilute the apologies will outrage South Korea, as well as China and the Philippines, which suffered under Japan’s brutal wartime rule.

Mr. Abe’s shameful impulses could threaten critical cooperation in the region on issues like North Korea’s nuclear weapons program. Such revisionism is an embarrassment to a country that should be focused on improving its long-stagnant economy, not whitewashing the past.